The source told AFP that the girl, aged 17, was on Sunday handed a five-year term for belonging to IS and one year in prison for crossing illegally into Iraq.
On January 21, a German woman of Moroccan origin was sentenced to death by hanging on charges of providing "logistical support and helping the terrorist group to carry out crimes".
The two Germans are among hundreds of foreign suspected jihadists held by Iraqi authorities, who in December announced the defeat of IS after a gruelling three-year battle.
At least two other German women are being held in prison in Iraq, including the teenager Linda W., who had disappeared from home in the summer of 2016, shortly after converting to Islam.
The girl from Pulsnitz in Saxony, in a meeting with German journalists in Baghdad last summer, said she wanted to return to her family and regretted her actions.
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